Commenter James Mann ‏at the link wrote: "They were playing hail to the chief. He's not going to salute himself. Grow up!"

What Mann wrote is an outright lie. At the time the photo was taken, someone was screeching a bast*rdized version of the National Anthem. There's a video of the goings-on, which you can watch and hear at Snopes.com, posted on 17 January 2015.